The Quest For Wonder Special Features – Episode 2
After hard day’s questing for Wonder with his puppet pal Professor Brian Cox, puppet Robin is left with a few questions. So after each episode he’s taking time to video chat with one of our Cosmic Genome scientists.
The Quest For Wonder Episode 2 Subscriber Exclusive
D.N.A. & Genetics with Dr Kat Arney
Robin - Hello Kat Arney. So, first things first. X-rays are what you look at to look at your bones, so how we use them to see DNA which, as far as I know, isn’t made of bones?
Kat - Well, the thing about the x-rays of DNA that were taken by Rosalind Franklin is that, even though you usually think of x-rays as going through bones, basically x-rays don’t go through solid stuff, and that includes atoms and molecules that DNA is made of. So just in the way that you can shine an x-ray through your foot and see if your bones are broken, you can shine an x-ray through a molecule of DNA, but instead of just getting a picture of the DNA, the DNA scatters these x-rays, but in a really characteristic pattern, and that’s what Rosalind Franklin saw in her x-ray of DNA, this kind of spiral pattern, that told her a good clue about what the structure was.
Robin - Right, if I’m honest, I can’t remember my entire genome, I can probably remember, like, the first 500 or 600 lines, but that would probably be a problem for rebuilding me so I want to know: why is the order of the Ts, Gs, Cs and As so important?
Kat - If you think about DNA or our genome, it’s basically like a load of recipes that tell ourselves what to do; they make stuff in our bodies, and just in the same way that the order of letters in a recipe in a book tells you exactly what to cook, the order of letters in our DNA tells a cell exactly what to make, and you can see why if you get a spelling mistake in your DNA that that might cause you problems: it can cause you health problems like cancer or other diseases, and just as the letters in a recipe tell us what to do, the letters in our DNA tell us what to do, so that’s why they’re kind of important.
Robin - So if I just add in extra bits to some DNA could I make super awesome animals with wings, and, like, with rhinoceros horns, or could I have armoured plates growing out of my spine, that kind of thing?
Kat - Lots of people want to know if you could maybe make a human grow a tail or something like that; if we could have super-senses like a bat’s ears or a cat’s eyes to see in the dark. It’s not really as simple as that: if you add genes to humans you’re still basically dealing with a human and we’ve got the structures and the developmental pathway that starts from an egg going to a human baby, and that’s kind of hard to tinker with. So, I don’t know, maybe you could add in some genes that might turn our skin a completely different colour, but if you’re talking about completely re-engineering what a human looks like: you know, how many legs you have or how many eyeballs you have, that’s probably going to be a bit more tricky.
Robin - So there’s not a chunk of DNA for heads and then a chunk for wings and a chunk for legs?
Kat - It’s not exactly the case that just one gene makes one thing in the body: there isn’t really a gene for a finger or an eyeball, it’s lots and lots of genes all working together and working through development as a baby grows, to make us turn out how we do, so it’s not as simple as saying ‘I’m going to take just one gene and change it’ and that’s going to have a completely different outlook on the baby or the person that comes out, but, you know, there are some things that can make quite big changes and some things that you have to get a lot of things all working together to make us who we are.
Robin - Since we found out about DNA how does that help prove Darwin right, even though he didn’t know about it?
Kat - We know that Darwin was a very, very clever man because he and some of the other people working around that time, they were looking at patterns of heredity: how traits are passed down from parents to children and through different animals as well, he was looking at rabbits and horses to see how their characteristics were passed on. And he figured out that there must be some kind of thing that passes from generation to generation with those traits. Now, you know, fast forward 100 years and we understand that genes are basically made from DNA - they’re instructions that tell our cells what to do - and we can now read the letters, the sequence of that DNA, in all kinds of organisms, from bacteria and yeast and plants to pandas and humans and dogs and cats and fish, and all sorts of things, even things that have maybe been extinct: we can get some of the DNA and we can look at it, and we can see that deep down we’re all related, all of life is related, and started from one common ancestor and has evolved in this beautiful tree of life, as Darwin thought, and that’s really proved him right.
Robin - Is it possible that Brian’s wonder is just part of his biology?
Kat - Lots of people say, is it nature, is it nurture, is it our DNA or is it our environment that makes you you, but in fact it’s both things working together. You can’t have a living thing without the environment it lives in and in our bodies our cells make an environment, they talk to each other, they tell each other to do things, or keep each other under control. And the environment we live in, that we grow up in, starting from your mum’s womb, will have an influence on how your genes work and how you come out. So really, everything works together: your upbringing, your environment, everything working with your genes to make you who you are. His hair may be partly genetic, but probably some good styling products, I reckon.
Robin - Suppose he, or anyone really, ate something that they weren’t meant to. Could that change our DNA and then our genes?
Kat - You can make changes in your DNA, and you probably don’t necessarily want to, because you can make changes to your DNA: they’re called mutations, and that happens with things like the chemicals in tobacco smoke, or if you spend too long in the sun the UV radiation from the sun can damage the DNA in your skin, and that can cause changes that can lead to cancer, so you really probably want to avoid those kind of things. And we know that, for example, some things like diet can influence the risk of cancer; we know, like I said, tobacco smoke, lots of UV rays from sun, those can all increase your risk of cancer by changing your genes in ways that you probably don’t want. DNA is really precious: it tells your cells what to do, it’s the instruction manual for life so, yeah, you want to try and look after it as much as you can, I think.
Robin - So, if we know all this, and we can write the human genome out in a big book, what does that help us with?
Kat - Now that we know everything that’s in the human genome, more or less, there are some bits that we still don’t really understand and we don’t know how it all works; we know that about 2% of our genome is actual genes and then a lot of the rest of it is stuff that we don’t really know about. Some of it is the switches that turn genes on and off; some of it may be kind of packing stuff; some of it we just don’t know yet and some of it may just be junk that we’ve collected through evolution in our genomes. But now we know what’s in there and we can start to do experiments to work out what is this gene, how does it work, how does it get turned on and off, how does it go wrong in diseases, maybe, like heart disease, or epilepsy, or Alzheimer’s, or cystic fibrosis, or cancer, we can start to really understand what causes those diseases, deep down at a molecular level, and then hopefully scientists can develop much better treatments or even work out how to prevent some of these diseases, and perhaps one day, with the new advances there’s been in genetic engineering and gene therapy, perhaps we can maybe cure people forever by making their genes better again.
Kat Arney’s new book ‘Herding Hemingway’s Cat: Understanding How Our Genes Work’, is out now.
Watch all episodes of The Quest For Wonder here.